Anticaking agent for cleansing



Patented Mar. 18, 1952 ANTICAKING AGENT FOR CLEANSING POWDER Puray "Bradford; Palos Park, ans j Herman .J.

White, Lansing;:Ill., assign'ors to Swift & Company, Chicago,--Ill., a corporation-of Illinois i No Drawing; Application-August '5, 1948;

Ser'ialNo. 42,743-- s Claims.- (c1. 252-440) This 1 invention relates to' mixtures of a powdered detergent and an abrasive, and more particularly to cleansing'powders having'therein trisodium phosphate and" silica;

Cleansing powders containing trisodium phosphate and silica are 'well" known, and such powders have been subject to caking under most normal atmospheric conditions and are thereby rendereddifiicult' to remove from a-package, and particularly from packages having= relatively small openings through whichthe powder is dis-' pense'd.

It'is an object of this invention to providea powdered mixture with an improved'anti-caking agent that will completely prevent caking and maintaining'the powder in a fluent state whereby it 'will be readily removed 'or "dispensed-from 'a' container.

It is a'further object of this invention to provide a powdered mixture-with an anti-caking" agent capable of maintaining the mixture ina' non-caking condition;'even when present in very small amounts.

Another object of this invention is to provide a powdered mixture containing silica and an alkali salt having water of crystallization thereinwhich, after prolonged storage, may be readily dispensedfrom a'container.

Other objects of the invention will be apparent from the description and claims to follow.

It is generally believed that powders containing trisodium phosphate and silica are subject to caking because of the formation of sodium silicate. And, as'is well known, sodium silicate is an efiicient adhesive the formation of which in a cleansing'powder would bond the particles together into a solid mass not suitable for being readily dispensed from a container having small discharge openings therein. -The sodium silicate is thought to be the result of areaction between silica and the sodium of the alkali salt in the presence of moisture. As the-alkali salt-trisodium phosphate contains several molecules of water of crystallization, there may be present a sufiicient amount of moisture to cause the objectionable reaction to take place even when moisture from the atmosphere is excluded. The latter is of considerable importance, since it explains the relative inefiectiveness as anti-caking agents for the instant powdered mixtures of those compounds which act simply to prevent the absorption of moisture from the atmosphere by the deliquescent substances. Thus, while the use of the latter type of anti-caking agents might have some efiect in preventing caking where deliquesnesium compounds in general, including magnesium phosphates, oxides, stearates, nitrates,-

sulphates, chlorides, palmitates, oleate's, as well as powdered magnesium metal, have superior anti-caking properties for the mixtures employed in the present invention;

While the magnesium compositions in general are superior to the non-moisture absorbent anticaking agents and to the chemical anti-caking agents, such as certain aluminum compounds,

nesium oxide because of its unexpected remarkable anti-caking qualities "in a trisodium phosphate and silica mixture. Applicants have discovered that as little as 0.1 per cent magnesium oxide will very efiectively prevent the caking of mixtures comprised substantially of finely divided silica and trisodium phosphate in all states of fineness. It has also been found that all grades of magnesium oxide may be'employed as antisticking agents. Thus, applicants have employed the following magnesium oxides to completely prevent caking of the aforesaid mixtures: U. S.

P. magnesium oxide-light, C. P. magnesium While as little oxide, and calcined magnesite. as 0.1 per cent U. S. P. magnesium oxide-light will efiectively prevent caking, it has been found desirable to employislightly larger amounts of the'heavier grades of magnesium oxides. For example, 0.2 per cent of calcined magnesite has been found to effectively prevent caking of the aforesaid mixtures. deleterious eiiect on the entire mixture and do not detract from the cleansing efficiency of-the product but, on the contrary, appear to impart a lubric'z'a'ting property to the mixture which improves its overall efiectiveness. instances it has been found desirable to employ 1 per cent magnesium oxide as an anti-caking agent. In other instances as much as 5 per cent of the anti-caking agent may be employed.

In addition to the above-mentioned magnesium oxide compound, the other magnesium compounds previously cited have been employed in similar proportions and have proved to be very effective as anti-caking agents when employed between approximately 0.5 per cent and Larger amounts have no Thus; in some 5 per cent. In addition to the particular ma iesium compounds set forth heretofore, ma iesium carbonate has also been found to be effec- ;ive as an anti-caking agent. The quantity of ;he carbonate necessary to prevent caking, how- :ver, is somewhat greater than the required mininum amounts of the other compounds.

In evaluating the effectiveness of the various mti-caking compositions, various mixtures were exposed to an accelerated caking test in which ;he powdered ingredients were placed in a shalow porcelain evaporating dish and placed in an )ven maintained at 140 F. at a relative humid- .ty of '70 per cent for a period of 16 hours. On :ooling to room temperature the contents of each :lish was discharged and examined for hard :rystalline masses or lumps. As an alternative nethod, the samples of cleanser were heated in 1. chamber maintained at a constant humidity of 37 per cent for a period of 3 hours and then :ransierred to a sieve and shaken in a mechanical maker for 2 minutes. The weight of the residue in the sieve was taken as a measure of the caking zendency of the cleanser. Each of the above ;ests is applicable to the present mixtures.

To further illustrate the present invention, the following specific examples are set forth:

Example I 30% trisodium phosphate 79.9% silica ).l% magnesium oxideU. S. P., light The powdered ingredients were intimately nixed and a portion of the mixture subjected to ;he 16-hour caking test previously described. No )bjectionable caking was observed.

Example II 20% trisodium phosphate 79.8 silica 3.2% calcined magnesite The powdered ingredients were intimately nixed and 30 grams of the resulting mixture subjected to the above-described 3-hour caking test. The amount of residue after the completion of the said test was less than 0.1 gram and was considered negligible.

Example III 22% trisodium phosphate 77% silica 1% calcined magnesite The powdered ingredients were intimately mixed and 30 grams of the mixture subjected to the 3-hour caking test, wherein a residue of approximately 0.2 gram was considered negligible.

Example IV 20% trisodium phosphate 78% silica 2% magnesium powder The powdered ingredients were intimately mixed and a portion of the mixture subjected to 4 the said 16-hour caking test. No objectionable caking was observed.

Example V trisodium phosphate mixed and a portion of the mixture subjected to the l6-hour caking test. No objectionable caking was observed.

While the foregoing description has referred particularly to trisodium phosphate as the alkali salt present in combination with the silica, it is to be understood that other alkali metal phosphate salts and other caustic alkali detergent compounds are within the scope of applicants invention. Also the abrasive composition employed by applicants should not be restricted to silica, since silica-containing mixtures, such as feldspar, are also within the purview of the present invention.

It should be obvious that various modifications will suggest themselves to those skilled in the art, and it should be understood that such modifications may be made without departing from the spirit and scope of this invention.

We claim:

1. A substantially non-caking cleansing powder consisting essentially of finely divided trisodium phosphate, particles of silica as an abrasive, and an amount from 0.1 to about 3 percent of a powdered anti-caking agent selected from the group consisting of metallic magnesium and compounds thereof.

2. A composition substantially as described in claim 1 wherein the anti-caking agent is powdered magnesium sulfate.

3. A composition substantially as described in claim 1 wherein the anti-caking agent is magnesium stearate.

4. A composition substantially as described in claim 1 wherein the anti-caking agent is magnesium oxide.

5. A composition substantially as described in claim 1 wherein the anti-caking agent is magnesium chloride.

6. A composition substantially as, described in claim 1 wherein the anti-caking agent is magnesium metal.

PURDY BRADFORD. HERMAN J. WHITE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,130,869 Block et a1 Sept. 20, 1938 2,257,545 Curtis Sept. 30, 1941 2,275,049 Keller Mar. 3, 1942 2,385,075 Gunther Sept. 18, 1945 

1. A SUBSTANTIALLY NON-CAKING CLEANSING POWDER CONSISTING ESSENTIALLY OF FINELY DIVIDED TRISODIUM PHOSPHATE, PARTICLES OF FINELY DIVIDED TRISODIUM AN AMOUNT FROM 0.1 TO ABOUT 3 PERCENT OF A POWDERED ANTI-CAKING AGENT SELECTED FROM THE GROUP CONSISTING OF METALLIC MAGNESIUM AND COMPOUNDS THEREOF. 